This invention relates to light dimming systems, and more particularly to apparatus for controlling the intensity of electric lamps for illumination control on television and theatrical stages or in similar applications where accuracy as well as specialized control are required to effect predetermined lighting cues.
To achieve the precise control of illumination required for television studio and stage lighting often requires as many as 400 separate lamps, and it may be desirable to vary the intensity of selected lamps or banks of lamps while leaving the intensity of other lamps or banks of lamps unchanged. Typical lighting control systems in current use utilize a multiplicity of power outlets arranged in a grid on a supporting structure above the stage or studio, with each of the multiplicity of lamps connected to a respective outlet. Alternating current power for the lamps is supplied to the outlet from a central power source, and control of the intensity of the individual lamps is achieved with a plurality of dimmers housed in a large assembly of dimmer racks and may include 40 to 60 or more dimmers of 6KW to 12KW each. Multiple conductors, one from each of the dimmers, are connected to a power patch selector panel from which power-carrying conductors are wired to the grid outlets. By preselected "patching" of the conductors from the dimmers and the conductors to the grid outlets, a given dimmer is operative to control the intensity of a given lamp or group of lamps. The dimmers are controlled from a lighting control console which houses control signal generating equipment, one for each of the dimmers. Such systems are complex, cumbersome (in that a large room is normally required to house the racks of dimmers), and expensive. For example, all currently available SCR dimmers suitable for stage use, regardless of their capacity, contain all of the elements necessary to provide control from the console, one of the more expensive components of which is the control circuit. Consequently, the initial cost of each individual dimmer is high and does not decrease proportionally with a decrease in dimmer capacity; that is, the cost of a 2KW dimmer, for example, is not significantly lower than the cost of a 12KW dimmer.